1. Field of the Invention
The present invention relates to an improved thermal sensing alarm structure, more particularly to a thermal sensing alarm with a lower casing having an embedding groove and terminal socket for accommodating the insertion of the power socket and long pin terminal on the circuit board to attain a very excellent fixing effect, and requires no traditional screw-and-nut connection and multiple soldering, but just needs to press down the circuit board for the assembling, and thus the present invention features the cost reduction.
2. Description of the Related Art
Traditional thermal sensing alarm structure generally includes the following features: a Fresnel lens provides a window for focusing the infrared ray of the human radiation; a sliding switch for the functional selection; a loudspeaker window for providing an outlet of alarm sound; and a battery compartment or DC power socket.
However, the detection is affected by the focal distance of the Fresnel lens and the size, position, and direction of mirror window, which makes the manufacture of the alarm with the aforementioned features very difficult and has the shortcomings of the high cost.
Please refer to FIG. 5. A close chassis is composed of an upper casing 60 with a Fresnel lens and a lower casing 70, and a circuit board 80 is disposed between the upper casing 60 and the lower casing 70; wherein the lower casing 60 has a screw post 61 each on both ends of the upper casing 60, a latching groove on both inner lateral sides each, a tubular post 71 disposed on each end of the upper casing 60, a wedge protruded on each lateral side, and a battery compartment 73 disposed at the lower section of the lower casing 70 and covered by a cover 74; the upper case 60 and a lower case 70 having a half axle base 63, 75 disposed at an appropriate position; and the two combine to form an axle for pivotally coupling to the base 76.
Before a circuit board 80 containing the components of the alarm system is coupled to the upper casing 60 and the lower casing 70, the battery button 100 of the power wire 101 should pass through the wire hole 77 of the lower casing 70, and the battery button 100 of the power wire 101 is soldered to the terminal of the externally connected DC power socket on the circuit board and two short screws 803 secure the DC power socket to the fixing post 78 of the lower case 70.
The circuit board 80 form a concave opening 81 each on both ends; when the circuit board 80 is placed on the lower casing 70, the two concave openings 81 exactly align with the inner margin of the tubular post 71, while the upper casing and the lower casing align with each other, not only snapped with each other by the embedding section 62 and the wedge 72, the screw post 61 also aligns with the tubular post 71 and the battery compartment 73 on the lower casing 70 having two screws 90 passing through the tubular post 71 of the lower casing 70, and being secured on the screw post 61 of the upper casing. The battery compartment 73 is covered by the close cover 74 such that the upper casing and the lower casing can hold the circuit board 80 in position for the assembling. A U-shape base 76 and axle base 63, 75 are pressed and pivotally coupled to constitute the complete structure.
However, the prior art structure described above does not have a good design, therefore the following shortcomings are found in the practice:
1. The prior-art power wire of the circuit board and the battery button wire soldered to the DC socket terminal is a secondary manufacturing process, and the power wire of the battery button must be passed through the wire hole of the lower casing, before the power wire is soldered onto the DC socket terminal. The complicated manufacturing process and the increase in cost are the shortcomings of the prior art.
2. When the upper casing and lower casing are assembled, the two small screws on the DC socket should be secured on the short posts of the lower casing, and the circuit board is placed on the lower casing, and the loudspeaker is attached on the isolating wall of the lower casing. After the upper casing and the lower casing are combined, the screws are passed through the bottom of the battery compartment for the fixing. Such two steps of fixing by screws increase the cost, and the operating procedure is complicated, which is another main shortcoming of the prior art.
The primary objective of the present invention is to design a screwless structure under the common requirements for the general thermal sensing alarm having a Fresnel lens, a sliding switch, a loudspeaker window, a battery compartment, or a DC power wire socket, which does not require a secondary terminal soldering manufacturing procedure, particularly the space restricted by the focal distance of the Fresnel lens affecting the general features of the thermal sensing alarm structure can be fully overcome. A refined, compact structure with simple manufacturing procedure can be accomplished. The assembling and manufacturing only require to pass the terminal of the battery button through the wire hole of the lower casing, and the DC power socket and long pin terminal on the circuit board are pressed and inserted into the embedded groove in the lower casing, and then the loudspeaker is attached on the wall in the lower casing. Then, the upper casing and the lower casing are pressed together, and a U-shape base and axle base are pressed and pivotally coupled to complete the combination. Such a simple manufacturing process gives an excellent fixing effect, and abandons the prior-art screw fixing procedure, which simplifies the manufacturing procedures and lowers the cost. The maintenance of the alarm according to the present invention is very convenient and thus can lower the cost.
To accomplish the foregoing objectives, the present invention uses the following method:
An upper casing and a lower casing constitute a close chassis, and a circuit board is fixed between the upper casing and the lower casing; wherein the upper casing at its appropriate position having a Fresnel lens; the lower casing at its bottom having a battery compartment, which is covered by a close cover; wherein the end of the lower casing at least having an embedding groove with appropriate width and a set of terminal slot; the power socket and the long pin terminal of the circuit board are soldered directly to lower section of the circuit board and exactly aligned with the embedding groove and the terminal slot, such that when the circuit board is pressed into the terminal slot, the fixing is done simultaneously. It does not only attain a good fixing effect, but also can save the trouble of fixing screws as done in the prior art, and make the assembling and maintenance very convenient.
To make it easier for our examiner to understand the objective of the invention, its structure, innovative features, and performance, we use a preferred embodiment together with the attached drawings for the detailed description of the invention.